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3 years ago

What's a streak plate?

1 answer:

3 0

An unglazed piece of porcelain, used to test the characteristic streak of minerals by rubbing the mineral across the tile. Streak plates have a hardness of about 6.5 on the Mohs scale and cannot be used for testing harder minerals.

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Dr. Matthews has submitted a proposal to the institutional review board (IRB) of a university. At this university, she intends t

OlgaM077 [116]

The IRB at the university will decide whether her study meets ethical guidelines before it is initiated. The importance of these codes of conduct is to safeguard research participants, the status of psychology and the researchers or psychologists themselves. Moral issues hardly yield a simple, unequivocal, right or wrong answer. It is consequently often a matter of judgment whether the research is justified or not. For instance, it might be that a study roots psychological or physical uneasiness to participants, maybe they agonize pain or maybe even come to solemn harm.

6 0

3 years ago

*A car is going through a dip in the road whose curvature approximates a circle of radius 150m. At what velocity will the occupa

Valentin [98]

Answer:

v= 14.85 m/s

Explanation:

When at the bottom of the dip, the only force that keeps the car in the circular trajectory, is the centripetal force.
This force is not a new force, is just the net force aiming to the center of the circle.
In this case, is just the difference between the normal force (always perpendicular to the surface, pointing upward) and the force that gravity exerts on the car (which is known as the weight), pointing downward.
So, we can write the following expression:

$F_{cent} = F_{n} - F_{g} (1)$

It can be showed that the centripetal force is related to the speed by the following expression:
$F_{cent} = m*\frac{v^{2}}{r} (2)$

The normal force, it is called the apparent weight, because it would be the weight as measured by a scale.
Replacing (2) in (1), and solving for Fn, we get:

$F_{n} = m*\frac{v^{2} }{r} + m*g (3)$

Now, we need to find the value of v that makes Fn, exactly 15% more than the weight m*g, so we can write the following equation:

$F_{n} = 1.15*F_{g} = m*\frac{v^{2}}{r} +F_{g} (4)$

Replacing Fg by its value, simplifying, and solving for v, we get:

$v = \sqrt{0.15*g*r} = \sqrt{9.8 m/s2*0.15*150m} = 14.85 m/s (5)$

3 0

2 years ago

A basketball is tossed up at an initial speed of 20 m/s.

qwelly [4]

Gravity slows the upward speed of any rising object by 9.8 m/s every second.

If the ball is tossed upward at 20 m/s, then it's at the top of its arc and its speed has dwindled to zero in (20/9.8) = 2.04 seconds.

During that time, its starting speed is 20 m/s and its ending speed is zero, so its AVERAGE speed all the way up is (1/2) (20 + 0) = 10 m/s .

Sailing upward for 2.04 seconds at an average speed of 10 m/s, the ball rises to (2.04 x 10) = <em>20.4 meters.</em>

4 0

2 years ago

The addition of electron shells results in<br><br> shielding of electrons from the nucleus.

Pani-rosa [81]

Answer:

Addition of shells increases the distance of outer electrons from the nucleus.

Explanation:

Shielding effect is known as the attraction between the nucleus and an electron of any atom. In other words, it is the reduction in effective nuclear charge on an electron cloud.

Addition of electron shells results in the shielding of electron from nucleus. As the number of electron shells increases then farther will be the electrons placed from the nucleus and hence it will become easier to expel the electrons from outer shells with only little amount of ionization energy.

So, the amount of ionization energy require will be indirectly proportional to the shielding effect because more the shielding of electrons from the nucleus less will be the ionization energy require to expel the electrons.

4 0

3 years ago

If a car with mass 750 kg is lifted to a height of 2.3 m how much gravitational potential energy is added to the car

Jlenok [28]

I found: 16,905J

Explanation:

The Gravitational Potential Energy will depend on the work done against gravity (weight, W=mg) to lift it at height h or:

U = mgh =750 * 9.8 *2.3 =16,905J

6 0

2 years ago